# distribution/hw03/modAddable.py               David MacQuigg  ece373  10/15/07

class Addable(object):
    '''Required methods to add two classes together.  Implementations over-
    riding these methods must be provided by each class.'''

    def __add__(self, other):
        '''Produce a sum of the lhs and rhs objects, without changing either.
        Return the sum as an object of the same type.'''

    def __neg__(self):
        '''Return the negative of this object, without altering the original.'''

    def __str__(self):
        '''Return the string value of this Addable ojbect.'''
   

